Review Article - Journal of Genetics and Molecular Biology (2023) Volume 7, Issue 1

Olfactory Receptors in Mammals including Bats

Among mammals, olfaction is employed to varied degrees in all facets of life, including the detection of food, the avoidance of predators, and social interaction. Additionally, different species have different olfactory capacities. Dogs and rodents, for example, depend on smell to travel, forage, and communicate. This is reflected in the number of functional OR genes present in these species. The mammalian genome contains the biggest gene family, the olfactory receptor (OR) gene repertoire, which encompasses over 1,000 functional OR genes, each of which codes for a distinct OR and is expressed sequentially in the cells of the olfactory epithelium. Binding of odors to ORs executes odor perception, which starts a signaling cascade to the brain's olfactory bulb through a G-protein coupled receptor. 13 monophyletic groups are supported by phylogenetic analysis of the nucleotide sequences of mammalian OR genes. Despite being highly annotated in the completed human and mouse genomes and making up 3 to 6% of mammalian genes, we still do not fully understand which odorants bind to which receptors and how this intricate process translates into perceiving a certain smell. Olfactory receptor genes expression can be discerned by looking at reasonably closely related species that have a wide variety of diets. Bats are potentially useful for this purpose. Bats (Chiroptera) represent one of the most fascinating mammal groups for studying OR gene expression studies. Fruit bats mainly employ olfaction in food detection and recently, many studies have revealed that the olfaction is linked to dietary specialization. Nevertheless, across very short distances, smell cues from mammals like bats can be more effective than vocalization. Conversely, several studies have examined the significance of olfaction in bat food acquisition and detection. While numerous comparative studies of nectarand fruit-eating bats have examined how olfaction and foraging ecology are related. In India, in fact, until recently, there is no systematic study of OR gene expression pattern in mega and micro bats. We employ molecular biology and bioinformatics techniques to identify the unique and diverse OR genomic repertoire in bats. Our preliminary results suggest that the total number of OR genes and families vary widely among both fruit and insect eating bats. If reflected in the diversity of OR genes, the large range of sensory specializations and modalities in bats could be used to explain the variety and uniqueness of the bat OR repertoire. In this review, the general structure and function of mammals' olfactory receptors, including those found in bats, are summarized.

Author(s): R. Steffi Christiane, T. Karuppudurai

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